Diprotic

Diprotic describes an acid which can donate two protons (H+) in an acid-base reaction. Sulfuric acid (H2SO4) is an example of a common diprotic acid, although this acid is in itself unusual as it is the only known strong diprotic acid. Carbonic acid, (H2CO3) is another common diprotic acid that is not strong. A weak acid is any acid that when immersed in water dissociates less than 100%.